Systems and processes for separating emulsified water from a fluid stream

ABSTRACT

Low-water content organic phases can be difficult to achieve at high fluxes when water is present in an emulsified form, such as in a water-in-oil emulsion. Processes for de-emulsifying a fluid stream containing emulsified water, such as water-in-crude oil emulsions, include introduction of the fluid stream into a vessel that defines a coalescence zone. The vessel is configured to provide for simultaneous application of a centrifugal force and an electric field to the fluid stream within the coalescence zone. The simultaneous application of the centrifugal force and the electric field to the fluid stream provides for the coalescence of a portion of the emulsified water into a bulk aqueous phase. Continuous phases of the organic component and the bulk aqueous phase form in the coalescence zone and are separately removed from the vessel. The bulk aqueous phase is removed from the underside of the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/874,488, filed on Oct. 5, 2015, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/060,261, filed Oct. 6, 2014.

FIELD OF THE INVENTION

The invention relates to a system and process for reducing the watercontent of water-in-organic emulsions, and, more specifically, to asystem and process for conducting high-flux separation of emulsifiedwater from an organic component, such as a water-in-oil emulsion.

BACKGROUND OF THE INVENTION

Many liquid-liquid separation processes involve the separation of waterfrom an organic phase. In such liquid-liquid separation processes, theformation of an aqueous phase that is immiscible with the organic phaseallows for separation of the two phases to take place from one anotherby a variety of means. In particular, the immiscibility of water withthe organic phase promotes partitioning between the aqueous phase andthe organic phase.

The separation of water from an organic phase can be much morecomplicated when the water is present in an emulsified form within theorganic phase, particularly when processing a water-in-oil emulsion. Insuch an emulsion, normal gravitational separation of the two phases doesnot occur by partitioning, or the partitioning process is so slow thatit is operationally limiting.

One way to promote breaking of emulsions so that partitioning occursmore readily is through adding various emulsion-breaking substances suchas surfactants, pH modifiers, salts and the like to the emulsion. Usingthese substances, however, increases the cost of processing the emulsionand impacts downstream operations. For example, using a surfactant tobreak water-in-oil emulsions may require removal of the surfactant fromthe organic phase before it is further processed. In another example,the use of a pH modifier to break a water-in-oil emulsion can alsorequire further modifying the pH of the separated aqueous phase so thatit can be suitably disposed of or further processed.

It is also costly to break emulsions using heat. Heating approaches areprohibitively expensive for many applications in which large fluidvolumes are processed.

Other techniques for breaking emulsions include applying a centrifugalforce to the emulsion. The application of centrifugal force to anemulsion results in coalescence of the small water droplets in theemulsion until the coalesced droplets increase sufficiently in size toform a bulk aqueous phase, also referred to as a continuous aqueousphase. Because of water's high mobility, it proceeds readily to theouter walls of a vessel in which a centrifugal force is being applied,while a water-depleted and less mobile organic phase remains more towardthe longitudinal center of the vessel. This allows for a location-basedseparation of the two phases to take place.

The application of an electric field to an emulsion also promotes thecoalescence of small water droplets into larger water droplets that morereadily form a bulk aqueous phase. U.S. Pat. Nos. 6,136,174 and8,591,714 describe illustrative processes and equipment for separatingemulsions through application of an electric field to the emulsion. Thedewatering processes disclosed in these patents, however, are limited inthe extent of dewatering that they provide.

Many applications and processes can benefit from utilizing organicphases having lower water contents than the presently availablehigh-flux dewatering techniques provide. Lower flux and more costlydewatering techniques are typically required to provide the organicphases with the low water levels needed for various applications andprocesses.

SUMMARY OF THE INVENTION

Accordingly, provided is a process for separating the components of awater-in-oil emulsion from one another. The process comprises:introducing a fluid stream comprising an organic component andemulsified water to a vessel defining a coalescence zone. The vessel isconfigured to simultaneously apply a centrifugal force and an electricfield to the fluid stream within the coalescence zone. The centrifugalforce and the electric field are simultaneously applied to the fluidstream within the coalescence zone so as to coalesce within thecoalescence zone a portion of the emulsified water into a bulk aqueousphase. Continuous phases of the organic component and the bulk aqueousphase are separately removed from the vessel. The bulk aqueous phase isremoved from the underside of the vessel.

Further provided is a system for separating the components of awater-in-oil emulsion from one another. The system comprises: a vesselhaving a fluid inlet and first and second fluid outlets. The vesseldefines a coalescence zone and is configured to apply a centrifugalforce to a fluid stream in the coalescence zone. An electricallyinsulated electrode having an elongated body is located within thevessel. The electrically insulated electrode is configured tosimultaneously apply an electric field to a fluid stream in the presenceof the centrifugal force. The first fluid outlet is configured to removea first component of the fluid stream from an underside of the vessel,and the second fluid outlet is configured to remove a second componentof the fluid stream from a top surface of the vessel after thecentrifugal force and the electric field have been applied to the fluidstream. The vessel has a longitudinal axis and is inclined with respectto the earth's surface. The longitudinal axis makes an incident anglewith the earths surface ranging between 20 degrees and 60 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustrating a system configured for separatingwater from an emulsified fluid stream.

FIGS. 2-4 are schematics of a vessel configured for the simultaneousapplication of an electric field and a centrifugal force to anemulsified fluid stream.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is related to systems and processes for conductinghigh-flux separation of emulsified water contained in an organiccomponent, including the high-flux separation of water from water-in-oilemulsions.

Electrostatic-based or centrifugal force-based separation processes areoften used independently in high-flux processes (defined in terms ofbbl/day/ft² or similar units) for removing water from water-in-oilemulsions having a high water content in the range, for example, of from30 vol. % to 80 vol. % water. With these processes, the final watercontent of the recovered organic phase is typically lowered to within arange of from 1 vol. % to 10 vol. %. A flux rate is considered to behigh when it is in the range of from 1,000 to 4,000 bbl/day/ft². Furtherdewatering of the emulsion to a concentration below 1 vol. %, however,is much more difficult to achieve by using these and other existingtechniques, even with iterative processing.

When processing an organic component having a low content of emulsifiedwater, the water droplets in the emulsion are too far apart from oneanother to undergo ready coalescence under the influence of either anelectrostatic-based process or a centrifugal force-based process.Because of this deficiency, techniques used to achieve furtherdewatering of water-in-oil emulsions having a low water contenttypically require operation at a much lower flux rate, such as a fluxrate in the range of less than 150 bbl/day/ft², or less than 100bbl/day/ft².

As indicated above, techniques for promoting separation of an aqueousphase from a water-in-oil emulsion (e.g., a water-in-oil emulsioncomprising a continuous organic phase and a discontinuous aqueous phase)having a high initial water content are generally limited in the extentof dewatering that they can provide at a high flux rate. Similarly,these separation techniques are much less effective when the initialwater content of the emulsion is low, such as less than 10 vol. % water,particularly, when the water content is in the range of from 1 vol. % to10 vol. %. As a result, even when cycling an emulsified water-in-oilfluid stream through multiple high-flux dewatering operations, it isdifficult to reduce the water content of the emulsion to the less than 1vol. % required for some applications. Because high-flux dewateringprocesses are typically unable to provide a dewatered organic phasehaving desired low water content, more costly lower flux dewateringtechniques are required to provide the dewatered organic phase.

To address the ongoing need for separation of water from an emulsifiedfluid stream, particularly a water-in-oil emulsion, the presentinventors discovered that various synergistic combinations of emulsioncoalescence techniques are more effective in promoting the formation ofa bulk aqueous phase from emulsified water droplets than the applicationof any of the techniques individually. The described techniques andsystems of the present disclosure provide for the processing of awater-in-oil emulsion under a high flux rate to yield a dewateredorganic component having a very low water content.

As used herein, the terms “emulsified water,” “emulsified waterdroplets” and related variants thereof refer to a fine dispersion ofwater droplets suspended in a continuous organic phase, such as ahydrocarbon or hydrocarbon mixture, wherein the water droplets do notseparate from the organic phase or do so only very slowly over time.

As used herein, the term “bulk aqueous phase” refers to a continuousphase comprising water.

The inventive systems and processes simultaneously apply both acentrifugal force and an electric field to a fluid stream comprisingemulsified water within an organic component. In particular, the fluidstream comprises a water-in-oil emulsion, such as emulsified water in acontinuous hydrocarbon phase. The simultaneous application of theseforces within a vessel promotes coalescence of the emulsified water intoa bulk aqueous phase within the vessel's coalescence zone. The resultingcontinuous phases are then removed from the vessel in separate streams.

The simultaneous application of a centrifugal force and an electricfield makes the inventive systems and processes particularly useful inseparating, under higher flux rates than are conventionally feasible,emulsified water from emulsified fluid streams having low initial watercontents. Thus, the inventive systems and processes allow forde-emulsification of inadequately dewatered emulsified fluid streams,such as water-in-oil emulsions having a low water content, at high fluxrates to produce a dewatered organic component. It should also berecognized that these systems and processes can be used for dewateringemulsified fluid streams having high initial water contents as well,such as emulsified fluid streams containing more than 20 vol. % water.In either case, the systems and processes are configured for producingat high flux rates an organic component having a low emulsified watercontent from an emulsified fluid stream. This feature advantageouslyfacilitates various subsequent high-volume applications that benefitfrom a low-water content organic component, such as petroleum refining.

Substantially vertical vessel orientations are usually used inconventional separator designs in order to minimize their lateralfootprint. Lateral footprint minimization is usually desirable in plantsettings, where physical space is at a premium. The inventors havefurther discovered that the inventive systems and processes benefit fromhaving a non-vertical disposition of a vessel in which the centrifugalforce and the electric field are applied to the emulsified fluid stream.

As used herein, the terms “non-vertical” or “inclined” refer to thedeviation of the longitudinal axis of an elongated vessel from a 90°incident angle with a plane parallel to the earths surface.

Despite the usual desirability of a substantially vertical vesselorientation, the benefits of a deviation from verticality may supersedethe benefits of lateral footprint minimization. Specifically, theinventors recognized that having a non-vertical or inclined surfacewithin the vessel better promotes coalescence of emulsified waterdroplets into a bulk aqueous phase and lowers the time required toseparate the organic component from the bulk aqueous phase. The benefitsof a deviation from verticality are particularly realized in combinationwith application of a simultaneously acting electric field andcentrifugal force.

The inventors believe that using an inclined vessel instead of avertical vessel to define the coalescence zone into which an emulsion isintroduced enhances the coalescence rate of water droplets within thecoalescence zone. This is thought to be due to the inclined vesselproviding for a shorter settling distance of the water droplets beforethey strike the inside wall of the inclined vessel. In addition,inclination also provides a larger inside wall contact area.

Moreover, the use of an inclined vessel increases the interfacialcontact area between two immiscible phases and promotes better phaseseparation once de-emulsification has taken place, as compared with theuse of a vertical vessel. A vertical vessel configuration minimizes boththe contact area at the vessel wall and the interfacial contact area.

The inventors have also identified alternative configurations in whichthe vessel itself is vertically oriented but has an inclined surfacefeature present within its coalescence zone. For example, an electrodeproviding the electric field within the vessel can be oriented at anangle with respect to the longitudinal axis of the vessel in order toprovide an inclined surface within the vessel. Inclined features withina substantially vertical vessel configuration produce similar benefitsto those provided by an inclined vessel.

Another advantageous feature of the invention is that, uponde-emulsification within the coalescence zone of the vessel, separationof the organic component and the bulk aqueous phase takes place withinthe coalescence zone of the vessel. Direct separation of the organiccomponent and the bulk aqueous phase within the coalescence zone occursdue to the differential localization of each phase in the presence ofthe centrifugal force.

In the inventive systems and processes, the more mobile aqueous phaseprogresses to the outer walls of the vessel's interior in the presenceof the centrifugal force, and the less mobile organic component remainsmore localized around the longitudinal axis of the vessel (i.e., furtheraway from vessel walls). Moreover, because of water's greater densityrelative to most organic components, specifically hydrocarbons,gravitational partitioning results in further localization of the bulkaqueous phase nearer the bottom of the vessel, adjacent to itsunderside. Accordingly, the inventive systems and processes can removethe bulk aqueous phase from the underside of the vessel. Similarly, theless dense organic component is removed from the top of the vessel.Directly separating the organic component from the bulk aqueous phasewithout using a downstream separation apparatus or separation means isparticularly advantageous for minimizing the footprint of the systems ina plant or other process setting.

As used herein, the term “underside” refers to a portion of the vesselhaving no other portion of the vessel located between it and the earth'ssurface. The underside of the vessel need not necessarily represent thebottom surface of the vessel. For example, in an inclined vessel, theunderside of the vessel may represent an exterior sidewall of thevessel, rather than a lower vessel surface that is perpendicular to thevessel's longitudinal axis. In an inclined vessel, the top surface ofthe vessel similarly need not necessarily represent a vessel surfacethat is perpendicular to the vessel's longitudinal axis.

Although the systems and processes can advantageously provide forseparating emulsified water from crude oil or other hydrocarbonresources under high-flux conditions, they are also applicable toseparating emulsified water contained within an organic component thatcomprises hydrocarbons found in various crude oil cuts. Examples ofcrude oil cuts that can be processed according to the invention includegasoline, diesel, kerosene, fuel oil, light vacuum gas oil, heavy vacuumgas oil, and any other mixture of hydrocarbon compounds.

In the co-production of water and oil from oil-bearing formations, thepresence of water in the oil, particularly as emulsified water,generally requires separation to provide a crude oil component suitablefor further processing in refinery operations. The generation of oilhaving a water content that is as low as possible is advantageous infurther refining of the oil. Residual water in oil can be exceedinglydetrimental to the refinery equipment. Moreover, contaminants carried bythe residual water can also be detrimental to the refinery equipment bycausing corrosion and scaling, and the contaminants can detrimentallyaffect the quality of products formed from the refined organiccomponent.

Since the systems and processes of the invention provide for high-fluxde-emulsification of water-in-oil emulsions and for the directseparation of the organic phase from the bulk aqueous phase, they areparticularly suitable for coupling to a continuous or semi-continuousrefining process. Particularly, these systems and processes canfacilitate refining processes by providing a low-water content organic(e.g., crude oil, hydrocarbon mixture, oil, and etc.) feed, while alsooffering improved product quality and protecting the refining equipmentfrom fouling by contaminants. In addition, they can operate at high fluxrates while still providing extensive dewatering of an organic feed. Forexample, the inventive systems and processes provide for a dewateredorganic stream having a water content of less than 1 vol. % whenprocessing the water-in-oil emulsion at a high flux rate of at least1,000 bbl/day/ft².

The inventive systems and processes will now be described with referenceto the drawings. FIG. 1 shows a general schematic of an illustrativesystem 100 configured for separating emulsified water from an emulsifiedfluid stream. As depicted in FIG. 1, an emulsified fluid stream entersvessel or hydrocyclone 110 of system 100 via fluid inlet line 120.Hydrocyclone 110 defines coalescence zone 112 and provides means forinducing rotational motion within the emulsified fluid stream introducedinto coalescence zone 112. This promotes the separation of the heavy(water) and light (oil) components of the introduced emulsified fluidstream by applying a centrifugal force.

Hydrocyclone 110 is configured to simultaneously apply a centrifugalforce and an electric field to the emulsified fluid stream while it iswithin coalescence zone 112. Hydrocyclone 110 can have either acylindrical or conical design or any other design that suitably providesfor coalescence of water droplets contained in the water-in-oilemulsion. The FIGS. and description below further describe particularlysuitable configurations for hydrocyclone 110 and structures forproducing an electric field E within hydrocyclone 110.

Within coalescence zone 112, the emulsified fluid stream undergoesseparation into an organic component (e.g., a continuous or bulk oilphase) and a bulk aqueous phase, with the bulk aqueous phase migratingtoward outer walls 116 and bottom surface 118 of hydrocyclone 110 underthe respective influences of the centrifugal force and gravity. The bulkaqueous phase is removed from hydrocyclone 110 by way of underside fluidoutlet line 140 on the underside of hydrocyclone 110. Underside fluidoutlet line 140 is located toward outer walls 116 of hydrocyclone 110 tobe better positioned to remove the bulk aqueous phase. Separating thebulk aqueous phase directly from hydrocyclone 110 desirably avoidsadding a discrete separator vessel or separator means downstream of thevessel, where physical space may be at a premium.

Still referring to FIG. 1, the organic component is withdrawn from thetop of hydrocyclone 110 through fluid outlet line 142. Fluid outlet line142 is located away from outer walls 116 of hydrocyclone 110, preferablyat or near longitudinal axis 144 of hydrocyclone 110. Positioning fluidoutlet line 142 in this manner places it in a better position to removethe less mobile organic component. Optionally, fluid outlet line 142extends into coalescence zone 112 in order to remove the organiccomponent. Accordingly, hydrocyclone 110 need not necessarily completelyfill to the top surface in order for removal of the organic component totake place.

Although the organic component within fluid outlet line 142 is oftensufficiently dewatered to support direct use thereof, further downstreamwater separation of the organic component may optionally take place.Separation of bulk water, even small amounts of bulk water, may takeplace readily through a variety of separation means. Accordingly, theorganic component removed via fluid outlet line 142 may optionally betransferred to a downstream separation apparatus or separation means(not shown), where further dewatering takes place. Suitable separationapparatuses or separation means include, for example, settling tanks,API separators, parallel plate separators, tilted plate separators,corrugated plate separators, air floatation separators, centrifuges,hydrocyclones, membrane separators, the like, and any combinationthereof.

Still other suitable downstream separation apparatuses or separationmeans include components of the separators described in U.S. Pat. No.8,591,714, which is incorporated herein by reference. As described inthis patent, elongated passageways provide for downward flow of waterand upward flow of an organic component, such as oil. A feed to theelongated passageways passes through an elongated inlet vesselcontaining an electrode. Such separation apparatuses may operate in acontinuous mode or in a semi-batch mode.

Solids can also be removed downstream of hydrocyclone 110. Theseparation of solids can take place in conjunction with separation ofresidual bulk water from the organic phase. In this regard, many of theseparation means and apparatuses described above can effectively promoteseparation of solids from the fluid phase of the organic component.

Further description follows with reference to FIGS. 2-4 of how theinvention simultaneously applies an electric field and a centrifugalforce to an emulsified fluid stream in a coalescence zone. Thediscussion first addresses the application of a centrifugal force to anemulsified fluid stream in a vessel.

System 200 of FIG. 2 shows hydrocyclone 210 that defines coalescencezone 212. Hydrocyclone 210 is equipped with fluid inlet line 220 that isfluidly connected to upper portion 230 and provides for tangentiallyintroducing an emulsified fluid into coalescence zone 212.Alternatively, fluid inlet line 220 is fluidly connected to conicalsection 240 of hydrocyclone 210, again with a tangential connection forpromoting rotational motion within coalescence zone 212. The emulsifiedfluid stream undergoes rotational motion within conical section 240 toproduce continuous phases of a bulk aqueous phase and an organiccomponent. The bulk aqueous phase exits hydrocyclone 210 through fluidoutlet line 250 and the organic component exits through fluid outletline 260.

As shown in the FIGS., electrode 270 is disposed within coalescence zone212. Electrode 270 provides means for conveying an electric field to theemulsified fluid stream introduced into and contained within coalescencezone 212. Electrode 270 conveys the electric field to the emulsifiedfluid stream while the emulsified fluid stream is experiencing or issubjected to a centrifugal force. Preferably, electrode 270 may beelongated and is configured so that it extends along or coincident tolongitudinal axis 275. Accordingly, electrode 270 extends through asubstantial portion of the longitudinal length of hydrocyclone 210 asdepicted in FIGS. 2 and 4.

In FIG. 3, electrode 270 is shown to deviate from longitudinal axis 275,such that electrode 270 is inclined with respect to the earths surface.Electrode 270 can also be parallel to and laterally offset fromlongitudinal axis 275. Further, multiple electrodes 270 can be used eventhough FIGS. 2-4 depict a single electrode 270. Electrode 270 isoperatively connected to means for providing electrical energy such aseither an AC or DC power source (not shown).

Electrical insulation can be provided on the exterior of electrode 270.Electrode 270 can be insulated so that it applies an electric field tothe emulsified fluid stream without directly applying a current to it.Electrode 270 can also have a substantially linear geometry such asdepicted in FIGS. 2-4. The geometry of electrode 270 minimizeschanneling of the emulsified fluid stream and its components withincoalescence zone 212. Electrode 270 can be either solid or tubular.

Electrode 270 can be insulated with any suitable dielectric coatingmaterial, including polymers that are typically used for providingelectrical insulation. It is preferable for electrode 270 to have acoating of the dielectric coating material when electrode 270 is used inprocessing an emulsified fluid stream having a high emulsified watercontent or an emulsified fluid stream having a high conductivity due tothe presence of a dissolved salt. When these conditions are not present,electrode 270 may be left uncoated, if desired. When electrode 270 isuncoated, it directly conveys both an electric current and an electricfield to the emulsified fluid stream.

Another feature of system 200 that can provide coalescence andseparation benefits is the placement of electrode 270 within coalescencezone 212. Electrode 270 can be parallel to or coincident withlongitudinal axis 275. Alternatively, electrode 270 can be oriented ordisposed within hydrocyclone 210 at an oblique angle with respect to theearths surface (or a plane situated parallel to the earth's surface).Accordingly, when hydrocyclone 210 is vertically disposed, as depictedin FIGS. 2 and 3, electrode 270 is inclined with respect to the earthssurface.

In the configuration of system 200 shown in FIG. 3, electrode 270 isnon-parallel to longitudinal axis 275. Specifically, electrode 270 isdisposed at angle θ with respect to plane 300. Plane 300 is parallel tothe earth's surface, and angle θ is less than 90 degrees. Preferably,angle θ is in a range from 20 degrees to 60 degrees, or in a range from22 degrees to 45 degrees.

In addition, both hydrocyclone 210 and electrode 270 can be oriented atan oblique angle with respect to plane 400. FIG. 4 illustrates thisgeometry. The oblique angle between longitudinal axis 275 and plane 400is less than 90 degrees with respect to the earth's surface.

As depicted in FIG. 4, hydrocyclone 210 and coalescence zone 212 aredisposed at angle θ1 with respect to plane 400 and electrode 270 isdisposed at angle θ2 with respect to plane 400. Plane 400 is parallel tothe earth's surface. When electrode 270 is disposed coincident with orparallel to longitudinal axis 275, angle θ1 and angle θ2 are equal toone another. However, if electrode 270 is not coincident with orparallel to longitudinal axis 275, angle θ1 and angle θ2 differ.

Particularly, angle θ1 is in a range from 20 degrees to 60 degrees. Morepreferably, angle θ1 is in a range from 22 degrees to 45 degrees. Stillmore preferably, angle θ1 is an angle greater than 30 degrees.

Angles θ1 and θ2 are chosen to promote coalescence of emulsified waterdroplets to a desired degree without requiring an overly large lateralfootprint of hydrocyclone 210. As discussed above, configuringhydrocyclone 210, electrode 270, or both into a non-vertical orientationcan be particularly beneficial for promoting gravitational coalescenceof water droplets at the wall of hydrocyclone 210 or at electrode 270 toform a bulk aqueous phase. This allows for an increase in the flux ratebut without reducing the amount of dewatering conveyed to the emulsifiedfluid stream. Indeed, this configuration even provides for anenhancement in the dewatering of the emulsified fluid stream.

The inventive systems can further include pre-conditioning separationmeans (not shown) for pre-conditioning the emulsified fluid stream forseparation. The pre-conditioning separation means is selected from thegroup consisting of a mechanical screen, an electrified screen, anelectrocoagulator, an electroprecipitator, and any combination thereof.

When pre-conditioning separation means is used, it is fluidly connectedto fluid inlet line 120 of hydrocyclone 110 of FIG. 1 or to fluid inletline 220 of hydrocyclone 210 of FIG. 2. This provides for upstreampre-conditioning of the emulsified fluid stream before introducing itinto either coalescence zone 122 or coalescence zone 212. Suchpre-conditioning of the emulsified fluid stream can further promote thecoalescence process within either coalescence zone 122 or coalescencezone 212.

The inventive systems thus comprise a vessel that defines a coalescencezone and has a fluid inlet and first and second fluid outlets. Thevessel is a hydrocyclone. The fluid inlet is configured to provide meansfor receiving or introducing an emulsified fluid stream into thecoalescence zone. The hydrocyclone is configured to provide means forapplying a centrifugal force to the emulsified fluid stream introducedinto and contained within the coalescence zone. An insulated, andusually elongated, electrode is positioned within the coalescence zoneof the hydrocyclone. The insulated electrode is disposed within thecoalescence zone so as to apply an electric field to the emulsifiedfluid stream in the presence of the centrifugal force. The first fluidoutlet is configured to provide means for removing a first component ofthe fluid stream from an underside of the vessel, and the second fluidoutlet is configured to provide means for removing a second component ofthe fluid stream from a top surface of the vessel after centrifugalforce and the electric field are applied to the fluid within thecoalescence zone. The hydrocyclone can be inclined with respect to theearth's surface so that its longitudinal axis makes an incident anglewith the earth's surface in a range of from 20 degrees to 60 degrees,and, preferably, of from 22 degrees to 45 degrees.

Optionally, the inventive systems optionally further comprise aseparation apparatus or separation means downstream from thehydrocyclone. Suitable separation apparatuses and separation meansinclude those described above. In addition, the separation apparatus orseparation means can also provide for removing solids that may bepresent in the organic component.

The insulated electrode can be placed within the vessel at an obliqueangle with respect to the vessel's longitudinal axis. That is, theinsulated electrode can deviate from verticality in a substantiallyvertical vessel configuration and make an oblique angle with the earth'ssurface. Thus, the insulated electrode makes an incident angle with theearth's surface in a range from 20 degrees to 60 degrees, or from 22degrees to 45 degrees.

As for the hydrocyclone, its longitudinal axis can also be inclined withrespect to the earth's surface, such that it makes an incident anglewith the earth's surface in a range of 20 degrees to 60 degrees, or from22 degrees to 45 degrees. In addition, the insulated electrode can beplaced or oriented within the coalescence zone of the hydrocycloneparallel to the longitudinal axis or in any other suitable orientationwith respect to the longitudinal axis.

The inventive processes provide for converting an emulsified fluidstream, such as a water-in-oil emulsion, into a continuous bulk water oraqueous phase and a continuous oil (organic) phase; and, then,separating the bulk aqueous phase from the organic phase. Separationoccurs in the coalescence zone of the vessel in which de-emulsificationtakes place. In a preferred process, the emulsified fluid stream is anemulsified crude oil or an emulsified fraction of crude oil.

The inventive processes include introducing an emulsified fluid streaminto a coalescence zone defined by a hydrocyclone. The hydrocycloneprovides means for simultaneously applying a centrifugal force and anelectric field to the emulsified fluid stream within the coalescencezone. This simultaneous application of the centrifugal force and theelectric field to the emulsified fluid stream that is introduced intothe coalescence zone provides for coalescence of a portion of theemulsified water to yield continuous phases of the organic component andwater component. These continuous phases are then separately removedfrom the vessel. The bulk aqueous phase is removed from the underside ofthe vessel. One or both of the continuous phases is removed from thevessel on a continuous basis.

The water droplets or particles of the water-in-oil emulsion are of asize in the range from of 10 nm to 100 microns. More typically, however,the water particles are in a range of from 25 nm to 10 microns, and,most typically, from 50 nm to 1 micron. Any combination or subrange ofthese droplet sizes may be present. Water droplet sizes above 100microns in diameter are considered to be a bulk aqueous phase forpurposes of the present disclosure.

The electric field applied in the inventive process can vary inmagnitude over a wide range, and the magnitude of the applied field canbe varied to achieve a desired degree of coalescence of emulsified waterdroplets. The applied voltage producing the electric field can be in therange of from 500 volts to 40,000 volts, and, more preferably, in arange of from 15,000 volts to 20,000 volts. The electric field isapplied with either an alternating current or a direct current.

The electric field is applied either continuously or it is pulsed. Whenpulsed, the pulse rate is in a range of from 0.1 Hz to 50 Hz, or from0.1 Hz to 10 Hz, or from 1 Hz to 5 Hz. Waveforms other than pulsing theapplied voltage can be used.

The rate at which the emulsified fluid stream is introduced into thecoalescence zone of the vessel is such as to provide a flux rate of atleast 1,000 bbl/day/ft² (bbl=barrel=42 US gallons) while still providingan organic component having a reduced water content below 1 vol. %. Thevalue used for the area term (ft²) of the flux formula is the effectivecross-sectional area of the vessel (i.e., of the plane area that isperpendicular to the vertical axis of the vessel) into which theemulsified fluid stream is introduced.

It is desirable for the flux rate of the inventive process to be as highas feasible. Thus, the flux rate can be in a range of at least 1,500bbl/day/ft² or at least 2,000 bbl/day/ft². Due to technical andpractical limits of the inventive process, there is a practical upperlimit to the flux rate. Therefore, the flux rate can be in the rangefrom 1,000 bbl/day/ft² to 6,000 bbl/day/ft², or from 1,500 bbl/day/ft²to 5,000 bbl/day/ft², or from 2,000 bbl/day/ft² to 4,500 bbl/day/ft², orfrom 2,500 bbl/day/ft² to 4,000 bbl/day/ft², or from 4,000 bbl/day/ft²to 5,000 bbl/day/ft². Conventional dewatering operations that arecapable of producing a water content below 1 vol. %, in contrast,generally operate at much lower flux rates that are typically less than100 bbl/day/ft².

As noted above, the inventive process provides a dewatered organiccomponent of the emulsified fluid stream having a water content below 1vol. % after separation of the continuous phases from one another. It ispreferred for the water content to be below 0.7 vol. % after separationof the continuous phases and even less than 0.6 vol. % or less than 0.3vol. %. It is even more preferred for the water content to be below 0.1vol. % or below 0.01 vol. % after separation of the continuous phases. Apractical lower limit for the water content is greater than 10 ppmv orgreater than 100 ppmv.

If the organic component still contains an unacceptably high content ofemulsified water after separation, the organic component can then berecycled to the vessel for further dewatering or it can be transferredto another vessel configured similarly to the ones described above.

Thus, multiple vessels configured to apply a centrifugal force and anelectric field to an emulsified fluid stream can be operativelyconnected in a series flow arrangement such that the water content ofthe organic component is decreased to a desired level. Alternatively,multiple vessels configured to apply a centrifugal force and an electricfield to an emulsified fluid stream can be operatively connected in aparallel flow arrangement to improve processing throughput or fluxrates. In addition, processing of the emulsified fluid stream can takeplace in a continuous, semi-continuous, or batch mode.

Not only can the inventive systems be used in series or parallel flowarrangements, but they can also be coupled with conventional separatorunits and processes. A number of configurations are possible in thisregard. Illustrative configurations include: the system connected in aseries flow arrangement with a conventional separator unit; the systemconnected in a parallel flow arrangement with a conventional separatorunit in which the conventional separator unit is the primary dewateringunit; or the system connected in a parallel flow arrangement with aconventional separator unit in which the conventional separator unit isa secondary or backup dewatering system.

Although the inventive systems and processes can be used for convertingany emulsified fluid stream into a dewatered organic component, they areparticularly applicable to emulsified fluid streams having a relativelylow initial content of emulsified water. In the inventive process, theemulsified fluid stream can contain emulsified water in an amount in arange from 0.5 vol. % to less than 10 vol. %, based on the volume of theemulsified fluid stream.

It is especially significant aspect of the inventive process that theemulsified fluid stream contains significantly less emulsified watersuch as amounts greater than 0.7 vol. % and less than 8 vol. %, oramounts greater than 0.9 vol. % and less than 5 vol. %, or amountsgreater than 1.2 vol. % and less than 3 vol. %.

Higher contents of emulsified water, such as between 15 vol. % to 80vol. % emulsified water can be addressed through conventional systemsand processes for de-emulsifying emulsified fluid streams, althoughemulsified fluid streams having water contents within this range arealso suitably addressed with the inventive systems and processes.

When the emulsified fluid stream comprises both bulk water andemulsified water, it is more desirable to remove the bulk water from theemulsified fluid stream before further processing takes place.Separation of bulk water is readily done by simpler, conventionalprocessing techniques. Accordingly, when an emulsified fluid streamcontains a significant amount of bulk water, it can first be processedusing conventional methods as described above to lower its watercontent. The emulsified fluid stream is then passed to the inventivesystems for processing by the inventive method.

The inventive processes can further comprise a step of adding a chemicalto the emulsified fluid stream to promote further coalescence of theemulsified water into the bulk aqueous phase. Suitable chemicalsinclude, for example, various polymers, surfactants, salts,de-emulsifiers, acids, and bases. The chemicals can be introduced intothe coalescence zone of the vessel, or they can be added or introduceddirectly into the emulsified fluid stream being introduced into thecoalescence zone of the vessel.

The organic component of the emulsified fluid stream is typically ahydrocarbon or mixture of hydrocarbons. The preferred feed of theinventive process is a water-in-crude oil emulsion or a water-in-crudeoil fraction emulsion. More specifically, the organic component of theemulsion comprises crude oil or a partially dewatered crude oil. Thus,the emulsified fluid stream can comprise as-obtained crude oil or crudeoil that has already been processed in a manner to remove a portion ofits water content.

When the emulsified fluid stream comprises crude oil or a partiallydewatered crude oil, the emulsified water may comprise formation water,or water that was introduced into a formation in conjunction withtreating or producing the formation, or any combination thereof. Theemulsified water associated with the crude oil can comprise a saltsolution or brine.

Other various components that can be present in the emulsified water,either alone or in combination with a salt, include chemicals used inthe course of treating or producing a formation such as, for example,polymers, breakers, gels, sealants, oxidants, anti-oxidants, amines andthe like. Metallic contaminants can also be present in the emulsifiedwater. Similarly, formation components such as salts of naphthenicacids, for example, can be present in the emulsified water.

Decreasing the content of emulsified water in a crude oil improves thequality of the yielded organic component. By practicing the invention,the amount of undesirable substances carried with the emulsified waterof a water-in-organic component (e.g., oil) emulsion and eventuallytransferred to the processed organic component is lessened. Decreasedcontaminant quantities in the organic component can be beneficial forvarious processes, particularly refining processes, where salt or othercontaminants from residual emulsified water cause issues such ascorrosion, precipitation, and fouling.

1. A process comprising: introducing a fluid stream comprising anorganic component and emulsified water to a vessel defining acoalescence zone, the vessel configured to simultaneously apply acentrifugal force and an electric field to the fluid stream within thecoalescence zone; simultaneously applying the centrifugal force and theelectric field to the fluid stream within the coalescence zone tocoalesce a portion of the emulsified water into a bulk aqueous phasewithin the coalescence zone; and separately removing from the vesselcontinuous phases of the organic component and the bulk aqueous phase,the bulk aqueous phase being removed from an underside of the vessel. 2.The process of claim 1, wherein the vessel is a hydrocyclone.
 3. Theprocess of claim 2, wherein the electric field is applied with anelectrically insulated electrode having an elongated body located withinthe coalescence zone of the vessel.
 4. The process of claim 3, whereinthe electrically insulated electrode has a non-concave exterior.
 5. Theprocess of claim 4, wherein the vessel has a longitudinal axis and theelectrically insulated electrode is non-parallel with respect to thelongitudinal axis.
 6. The process of claim 5, wherein the vessel has alongitudinal axis and is inclined with respect to the earth's surface,thereby making an incident angle with the earth's surface in a rangefrom 20 degrees to 60 degrees.
 7. The process of claim 6, wherein theorganic component comprises a crude oil or a partially dewatered crudeoil.
 8. The process of claim 7, wherein the fluid stream comprises lessthan 10% water by volume.
 9. The process of claim 8, wherein the fluidstream is introduced to the vessel after passing through a mechanicalscreen, an electrified screen, an electrocoagulator, anelectroprecipitator, or any combination thereof.
 10. The process ofclaim 9, further comprising: adding a chemical to the fluid stream tofurther promote coalescence of the emulsified water into the bulkaqueous phase.
 11. The process of claim 10, wherein at least one of thecontinuous phases is removed from the vessel on a continuous basis.